A rotary engine used in an automobile or the like comprises a rotor housing; a side housing and an intermediate housing arranged in such a manner as to sandwich the rotor housing from both sides thereof; a rotor accommodated rotatably in the rotor housing; side seal grooves formed respectively on both side surfaces of the rotor facing the side housing and the intermediate housing; side seals accommodated respectively in the side seal grooves; and apex seals disposed at apexes of the rotor.
In the side seals of the rotary engine, end faces thereof at positions projecting from the side seal grooves are urged toward and are made to slidably abut against the side housing and the intermediate housing that face the end faces, respectively, by means of springs accommodated in the side seal grooves, thereby attaining primary gastightness with respect to an engine operating chamber. The rotor axis-side side surfaces of the side seals are urged toward and are made to slidably abut against side wall surfaces of the side seal grooves facing those respective side surfaces by means of gas pressure and the like, thereby attaining secondary gastightness with respect to the engine operating chamber.
Since the side seal has a long length, and distances from the rotor center to respective positions thereof differ, the magnitudes and directions of sliding resistance and inertial force at the respective positions thereof differ respectively. For this reason, each side seal abuts against the side wall surface of the side seal groove in an unnatural posture. In addition, the frictional resistance of contact between the side seal and the side wall surface of the side seal groove is large (which is considered to be 0.1 to 0.3 in terms of a coefficient of friction), and even if the side seal is subjected to a lifting force by the gas pressure inside the side seal groove when the side seal is pressed against the side wall surface of the side seal groove by the gas pressure from the engine operating chamber, the behavior of the side seal is poor, and the sliding contact of the side seal with respect to the side housing is not established sufficiently. For this reason, high-temperature gases burst out from the gap between the side seal and the side housing, thereby resulting in the overheating of the rotary engine and causing damage to a rotor oil seal. This overheating of the rotary engine causes deformation of the rotary engine, i.e., deformation of the side housing, thereby resulting in a vicious circle of bringing about further gas leakage.
In particular, combustion gases leaking from the side seal circulate to the intake side and are sucked in by being mixed with a fresh intake gas, thereby constituting a cause of misfiring and resulting in a decline in output.
The present invention has been devised in view of the above-described aspects, and its object is to provide a rotary engine which increases the mobility of each side seal in the side seal groove toward the sliding surfaces of the side housing and the intermediate housing so as to prevent a gap from being formed between an end face of the side seal and the respective sliding surfaces of the side housing and the intermediate housing, thereby making it possible to attain primary gastightness more reliably without deteriorating secondary gastightness.